The present application is based on Japanese Patent Application No. 10-337696 filed Nov. 27, 1998, the contents of which are incorporated hereinto by reference.
1. Field of the Invention
The present invention relates to a blood pressure monitor apparatus which monitors a blood pressure of a living subject based on blood pressure-relating information which changes with a change of the blood pressure of the subject.
2. Discussion of the Related Art
There has been proposed a blood pressure monitor apparatus which successively obtains blood pressure-relating information of a living subject (patient) and judges abnormality of the blood pressure when the blood pressure-relating information is greater than a predetermined upper reference value or smaller than a predetermined lower reference value. The blood pressure-relating information includes a blood pressure which is measured by using a catheter or a cuff, pulse-wave propagation velocity-relating information such as a pulse-wave propagation velocity at which a pulse wave propagates through an artery or a pulse-wave propagation time during which a pulse wave propagates between predetermined two portions of an artery, heart rate-relating information such as a heart rate or a pulse period which changes due to conditions of a central organ (heart) of the subject, peripheral blood volume-relating information such as a peripheral pulse-wave area which indicates a peripheral blood volume and which changes due to conditions of a peripheral organ (blood vessels) of the subject, and blood oxygen saturation. The above-indicated conventional blood pressure monitor apparatus which monitors the blood pressure-relating information automatically determines abnormality of the blood pressure of the subject based on the obtained blood pressure-relating information, so that the abnormal condition of the patient can be quickly dealt with.
The conventional blood pressure monitor apparatus determines abnormality of the blood pressure of the patient when the detected or obtained blood pressure-relating information is greater than a predetermined upper reference value or smaller than a predetermined lower reference value. Accordingly, the conventional blood pressure monitor apparatus equally determines abnormality of the blood pressure due to an abrupt change thereof in a considerably short period of time and due to a gradual change thereof in a relatively long period of time. In general, the abnormal condition of the patient detected when the blood pressure-relating information has abruptly changed should be dealt with as quickly as possible, as compared with that detected when the blood pressure-relating information has gradually changed. The conventional apparatus described above, however, cannot assure that a suitable medical treatment is given without delay on the patient whose blood pressure-relating information has abruptly changed.
It is therefore an object of the present invention to provide a blood pressure monitor apparatus which is capable of quickly detecting abnormality of the blood pressure of a patient when the blood pressure has changed abruptly.
The above object may be attained according to a first aspect of the present invention, which provides a blood pressure monitor apparatus for monitoring a blood pressure of a living subject, comprising: blood pressure-relating information obtaining means for successively obtaining blood pressure-relating information which decreases with a decrease of the blood pressure of the subject; decrease determining means for determining a decrease of the blood pressure-relating information successively obtained by the obtaining means; and abnormality judging means for judging that the blood pressure of the subject is abnormal when the decrease of the blood pressure-relating information is greater than a predetermined reference value (xcex31).
The above object may also be attained according to a second aspect of the present invention, which provides a blood pressure monitor apparatus for monitoring a blood pressure of a living subject, comprising: blood pressure-relating information obtaining means for successively obtaining blood pressure-relating information which increases with a increase of the blood pressure of the subject; increase determining means for determining an increase of the blood pressure-relating information successively obtained by the obtaining means; and abnormality judging means for judging that the blood pressure of the subject is abnormal when the increase of the blood pressure-relating information is greater than a predetermined reference value (xcex32).
The above object may also be attained according to a third aspect of the present invention, which provides a blood pressure monitor apparatus for monitoring a blood pressure of a living subject, comprising: blood pressure-relating information obtaining means for successively obtaining blood pressure-relating information which decreases with an increase of the blood pressure of the subject; decrease determining means for determining a decrease of the blood pressure-relating information successively obtained by the obtaining means; and abnormality judging means for judging that the blood pressure of the subject is abnormal when the decrease of the blood pressure-relating information is greater than a predetermined reference value (xcex32).
The above object may also be attained according to a fourth aspect of the present invention, which provides a blood pressure monitor apparatus for monitoring a blood pressure of a living subject, comprising: blood pressure-relating information obtaining means for successively obtaining blood pressure-relating information which increases with a decrease of the blood pressure of the subject; increase determining means for determining an increase of the blood pressure-relating information successively obtained by the obtaining means; and abnormality judging means for judging that the blood pressure of the subject is abnormal when the increase of the blood pressure-relating information is greater than a predetermined reference value (xcex31).
In the blood pressure monitor apparatuses constructed as described above, the decrease or increase determining means determines a decrease or an increase of the blood pressure-relating information successively obtained by the blood pressure-relating information obtaining means, and the abnormality judging means judges that the blood pressure of the living subject (patient) is abnormal when the decrease or increase of the blood pressure-relating information is greater than the predetermined reference value. In other words, when the blood pressure-relating information has abruptly decreased or increased, the abnormality judging means judges that the blood pressure of the patient is abnormal even if the blood pressure-relating information may be normal or permissible. Accordingly, the abnormality of the blood pressure of the patient can be detected without delay when the blood pressure has abruptly decreased or increased.
In a preferred form of the above first or fourth aspect of the present invention, the blood pressure monitor apparatus further comprises reference value determining means for determining the reference value (xcex31) based on the blood pressure-relating information successively obtained by the obtaining means, by utilizing a predetermined relationship between reference value and blood pressure-relating information, the relationship being predetermined such that a smaller reference value corresponds to blood pressure-relating information corresponding to a lower blood pressure.
According to the above preferred form of the first or fourth aspect of the invention, the reference value determining means determines the reference value (xcex31) which is used in judging the abnormality of the blood pressure of the patient by the abnormality judging means, such that a smaller reference value corresponds to blood pressure-relating information corresponding to a lower blood pressure. According to this arrangement, when the blood pressure of the patient is relatively low, the abnormality judging means judges that the blood pressure of the patient is abnormal even if the decrease or increase of the blood pressure-relating information may be relatively small, so that the abnormality of the blood pressure of the patient can be quickly detected without delay when the blood pressure has abruptly decreased. When the blood pressure of the patient is not so low, the abnormality judging means judges that the blood pressure of the patient is abnormal only when the decrease or increase of the blood pressure-relating information is relatively large, so that the judgment of the abnormality of the blood pressure is prevented when the blood pressure of the patient is not so low. In the case where the abnormality of the blood pressure is determined on the basis of only the decrease or increase of the blood pressure-relating information, the reference value must be set at a small value in an attempt to be able to find an abnormal blood pressure even if the blood pressure may gradually decrease. In this case, however, the blood pressure may unnecessarily be judged to be abnormal when the blood pressure is not so low.
In a preferred form of the above second or third aspect of the invention, the blood pressure monitor apparatus further comprises: reference value determining means for determining the reference value (xcex32) based on the blood pressure-relating information successively obtained by the obtaining means, by utilizing a predetermined relationship between reference value and blood pressure-relating information, the relationship being predetermined such that a smaller reference value corresponds to blood pressure-relating information corresponding to a higher blood pressure.
According to the above preferred form of the above second or third aspect of the present invention, the reference value determining means determines the reference value (xcex32) which is used in judging abnormality of the blood pressure of the patient by the abnormality judging means, such that a smaller reference value corresponds to the blood pressure-relating information corresponding to a higher blood pressure. According to this arrangement, when the blood pressure of the patient is relatively high, the abnormality judging means judges that the blood pressure of the patient is abnormal even when the increase or decrease of the blood pressure-relating information may be relatively small, so that the abnormality of the blood pressure of the patient can be quickly detected without delay when the blood pressure has abruptly increased. In contrast, when the blood pressure of the patient is not so high, the abnormality judging means judges that the blood pressure of the patient is abnormal only when the increase or decrease of the blood pressure-relating information is relatively large, so that the determination of the abnormality of the blood pressure is prevented when the blood pressure of the patient is not so high. In the case where the abnormality of the blood pressure is determined on the basis of only the increase or decrease of the blood pressure-relating information, the reference value must be set at a small value in an attempt to be able to find an abnormal blood pressure of the patient even when the blood pressure may gradually increase. In this case, however, the blood pressure may unnecessarily be determined to be abnormal when the blood pressure is not so high.
In a preferred form of the above first or third aspect of the invention, the decrease is selected from the group consisting of an amount of decrease of the blood pressure-relating information and a rate of decrease of the blood pressure-relating information.
In a preferred form of the above second or fourth aspect of the invention, the increase is selected from the group consisting of an amount of increase of the blood pressure-relating information and a rate of increase of the blood pressure-relating information.
In a preferred form of the above first or second aspect of the invention, the blood pressure-relating information is selected from the group consisting of an estimated bloodpressure (EBP), a normalizedpulse-wave area (SF), and a pulse-wave propagating velocity (VM).
In a preferred form of the above third or fourth aspect of the invention, the blood pressure-relating information comprises a pulse-wave propagation time (DT).
The above-indicated object of the present invention may also be attained according to a fifth aspect of the invention, which provides a blood pressure monitor apparatus for monitoring a blood pressure of a living subject, comprising: blood pressure-relating information obtaining means for successively obtaining blood pressure-relating information which decreases with a decrease of the blood pressure of the subject; abnormality judging means for judging that the blood pressure of the subject is abnormal when the blood pressure-relating information successively obtained by the obtaining means is smaller than a predetermined reference value (THL); decrease determining means for determining a decrease of the blood pressure-relating information successively obtained by the obtaining means; and reference value determining means for determining the reference value (THL) based on the decrease of the blood pressure-relating information successively obtained by the obtaining means, by utilizing a predetermined relationship between reference value and decrease of blood pressure-relating information, the relationship being predetermined such that a greater reference value (THL) corresponds to a greater decrease of blood pressure-relating information.
In the blood pressure monitor apparatus constructed as described above, the reference value determining means determines the reference value THL which is used in judging abnormality of the blood pressure of the subject by the abnormality judging means, based on the decrease of the blood pressure-relating information successively obtained by the obtaining means, by utilizing a predetermined relationship between reference value and decrease of the blood pressure-relating information, the relationship being predetermined such that a greater reference value (THL) corresponds to a greater decrease of the blood pressure-relating information. Further, the abnormality judging means judges that the blood pressure of the subject has abnormally decreased when the blood pressure-relating information obtained by the obtaining means is smaller than the reference value (THL). According to this arrangement wherein a greater reference value corresponds to a greater decrease of the blood pressure-relating information, the abnormality judging means judges abnormal decrease of the blood pressure of the subject without delay when the blood pressure has abruptly decreased. In addition, since a smaller reference value corresponds to a smaller decrease of the blood pressure-relating information, the present arrangement prevents determination of abnormal decrease of the blood pressure when the blood pressure of the subject is not so low and the blood pressure has gradually decreases.
In a preferred form of the above fifth or sixth aspect of the invention, the blood pressure-relating information is selected from the group consisting of an estimated blood pressure (EBP), a pulse-wave propagation velocity (VM) and a normalized pulse-wave area (SF).
The above-indicated object of the present invention may also be attained according to a sixth aspect of the invention, which provides a blood pressure monitor apparatus for monitoring a blood pressure of a living subject, comprising: blood pressure-relating information obtaining means for successively obtaining blood pressure-relating information which increases with an increase of the blood pressure of the subject; abnormality judging means for judging that the blood pressure of the subject is abnormal when the blood pressure-relating information successively obtained by the obtaining means is greater than a predetermined reference value (THH); increase determining means (60) for determining an increase of the blood pressure-relating information successively obtained by the obtaining means; and reference value determining means for determining the reference value (THH) based on the increase of the blood pressure-relating information successively obtained by the obtaining means, by utilizing a predetermined relationship between reference value and increase of blood pressure-relating information, the relationship being predetermined such that a smaller reference value (THH) corresponds to a greater increase of blood pressure-relating information.
In the blood pressure monitor apparatus constructed as described above, the reference value determining means determines the reference value THH which is used in judging abnormality of the blood pressure of the subject by the abnormality judging means, based on the increase of the blood pressure-relating information successively obtained by the obtaining means, by utilizing a predetermined relationship between reference value and increase of the blood pressure-relating information, the relationship being predetermined such that a smaller reference value (THH) corresponds to a greater increase of the blood pressure-relating information. Further, the abnormality judging means judges that the blood pressure of the subject has abnormally increased when the blood pressure-relating information obtained by the obtaining means is greater than the reference value. According to this arrangement wherein a smaller reference value corresponds to a greater increase of the blood pressure-relating information, the abnormality judging means judges abnormal increase of the blood pressure of the subject without delay when the blood pressure has abruptly increased. In addition, since a greater reference value corresponds to a smaller increase of the blood pressure-relating information, the present arrangement prevents determination of abnormal increase of the blood pressure when the blood pressure of the subject is not so high and the blood pressure gradually increases.
The above-indicated object of the present invention may also be attained according to a seventh aspect of the invention, which provides a blood pressure monitor apparatus for monitoring a blood pressure of a living subject, comprising: blood pressure-relating information obtaining means for successively obtaining blood pressure-relating information which decreases with an increase of the blood pressure of the subject; abnormality judging means for judging that the blood pressure of the subject is abnormal when the blood pressure-relating information successively obtained by the obtaining means is smaller than a predetermined reference value (THL); decrease determining means for determining a decrease of the blood pressure-relating information successively obtained by the obtaining means; and reference value determining means for determining the reference value (THL) based on the decrease of the blood pressure-relating information successively obtained by the obtaining means, by utilizing a predetermined relationship between reference value and decrease of blood pressure-relating information, the relationship being predetermined such that a greater reference value (THL) corresponds to a greater decrease of blood pressure-relating information.
The above-indicated object of the present invention may also be attained according to an eighth aspect of the invention, which provides a blood pressure monitor apparatus for monitoring a blood pressure of a living subject, comprising: blood pressure-relating information obtaining means for successively obtaining blood pressure-relating information which increases with a decrease of the blood pressure of the subject; abnormality judging means for judging that the blood pressure of the subject is abnormal when the blood pressure-relating information successively obtained by the obtaining means is greater than a predetermined reference value (THH); increase determining means for determining an increase of the blood pressure-relating information successively obtained by the obtaining means; and reference value determining means for determining the reference value (THH) based on the increase of the blood pressure-relating information successively obtained by the obtaining means, by utilizing a predetermined relationship between reference value and increase of blood pressure-relating information, the relationship being predetermined such that a smaller reference value (THH) corresponds to a greater increase of blood pressure-relating information.
In a preferred form of the above fifth or seventh aspect of the present invention, the decrease is selected from the group consisting of an amount of decrease of the blood pressure-relating information and a rate of decrease of the blood pressure-relating information.
In a preferred form of the above sixth or eighth aspect of the present invention, the increase is selected from the group consisting of an amount of increase of the blood pressure-relating information and a rate of increase of the blood pressure-relating information.
In a preferred form of the above fifth or sixth aspect of the present invention, the blood pressure-relating information is selected from the group consisting of an estimated blood pressure (EBP), a pulse-wave propagation velocity (VM) and a normalized pulse-wave area (SF).
In a preferred form of the above seventh or eighth aspect of the present invention, the blood pressure-relating information comprises a pulse-wave propagation time (DT).